Compressor-unloading device



March 27, 1928. I 1,663,687

S. G. DOWN oommmsson UNLOADING DEVICE Filed June 1. 1927 iii /6 INVENTORSIDNEYGDOWN ATTORNEY Patented lViar. 27, 1928.

SIDNEY G. DOWN, OF EDGEWOOD, PENNSYLVANIA, ASSIGNOR TO THE WESTINGHOUSEi AIR BRAKE COMPANY, OF WILMERDING, PENNSYLVANIA, LA CORPORATION OFIPENNSYLVANIA.

Application filed June 1,

more particularly for a compressor having an inlet valve of the sleevetype.

In the accompanying drawing, Fig. 1 1s a central sectional view of afluid compressor 1 p 7 shown diagrammatically in Fig. 2 and indiwith myinvention applied thereto; and Fig. 2 a diagrammatic view showing thearrangement of the electric control for the unloading device. I i

The construction shown in the drawing comprises a cylinder casing 1containing a sleeve or liner 2. A compressor piston 3 is adapted toreciprocate within the sleeve 2 i and the sleeve is moved up and downwith the piston by the ring friction of the usual piston rings. I I

The upper end of the sleeve 2 is provided with a valve portion 4 adaptedto engage a valve seat member 5. i

The valve portion 4 is provided with a central opening, through whichflows fluid compressed in the chamber 6 above the piston 3, said openingbeing connected to the discharge passage 7. A check valve 8, subject tothe pressure of a coil spring 9, prevents back flow from passage 10 topassage 7 the passage 10 being connected to a suitable fluid storagereservoir (not shown).

An annular chamber 11 surrounds the upper portion of the sleeve 2 and isopen to the atmosphere at 12. I

Preferably adjacent to the upper end, the sleeve 2 is provided with aflange'13 which limits the downward movement of the sleeve 2 byengagement with a magnet core ring 14,

having a magnet coil 15. The ring 14 and the coil 15 are mounted 011 anannular flange 16 of the casing 1 and the energization anddeenergization of the coil is controlled by a switch device adapted tomaintain the coil energized when the compressor is operating and thepressure of compressed fluid is being built up to the desired limit.When the pressure has been increased to a predetermined limit, theswitch device operates to open the circuit of the coil and permit thedeenergization thereof.

For this purpose, a switch device may be employed such as the well knowncompressor governor such, for example, as that shown in Patent No.1,018,594 of W. V. Turner, dated February 27, 1912, except that thecircuit coMPnEssoR-UnLoAnING nnvrcn,

1927. Serial no. 195,623.

is opened when the pressure inthe storage reservoir is less than thepredetermined degree, 311C115 closed when the pressure of fluidcompressed by the compressor into the storage reservoir has beenincreased to the predetermined degree.

A switch device of the above character is lingers 20. connected incircuit with the 'coil 15. Included in the circuit is a source ofcurrent '21.

Inoperation, when the piston 3 is reciprocating in the sleeve 2 and thepressure 0 fluid in the storage reservoir is belowthe predetermineddegree the switch device '17 operates to hold the stem 18 in its lowerposition, in which the contacts 19 are not in engagement with thefingers 20 and consequently the circuit of the coil 15is open and thecoilis deenergized. The piston then operates by the frictionalresistance of its piston rings to move the sleeve 2 up and down. On thedown stroke, the sleeve is moved so that theflange 13 engages thevmagnet ring 14, and the valve portion 4 being away from its seat 5,fluid from the atmosphere flows into the chamber 11 and thence past theunseated valve portion 4 to the piston chamber 6.

Upon the up-stroke of the piston 3, the sleeve 2 is moved upwardly sothat the valve portion 4 engages the seat 5, and fluid compressed by thepiston within the piston chamber 6 flows through passage 7 past thecheck valve 8 to passage 10 and thence to the storage reservoir.

When the pressure in the storage reser V011 has been increased to apredetermined degree byoperation of the compressor, the

switch device 17 is'operated so as to causethe upward movement of thestem 18 and the engagement of the contacts 19 with the fingers 20.

The circuit of the coil 15 is thus closed and the coil is energized. Thering 14 then becomes magnetized and the magnetic force exerted by thering on the flange 13 is sufficient to hold the flange and the sleeve 2in the downward position, and since the valve portion 4 is thusprevented from seating on the seat portion 5, the reciprocation of thewhen the switch device 17 again operates to open the circuit of themagnet coil 15, so

' that the sleeve valve 2 is permitted to operate with the piston.

Having now described my invention, What I claim as new and desire tosecure by Letters Patent, is 1. In a fiuid compressor, the combinationwith a cylinder casing having a movable sleeve and a piston in saidsleeve, said sleeve being moved by friction of said piston, of meanscontrolled by the pressure of fluid compressed by the compressor forpreventing the movement of said sleeve by said piston. V

2. In a fluid compressor, the combination with a cylinder casing havinga movable sleeve valve and apiston in said sleeve, of

means for preventing the movement of said sleeve valve when the pressureof fluid compressed by the compressor has been increased to apredetermined degree.

3. In a fluid compressor, the combination with a cylinder casing havinga movable sleeve acting as the inlet valve for said compressor and apiston in said sleeve, said sleeve being moved by friction with saidpiston, of means for holding said sleeve valve in the open positionwhile the pressure of fluid compressed by the compressor exceeds apredetermined degree;

4. In a fluid compressor, the combination with a cylinder casing havinga movable sleeve and a piston in said sleeve, of electriwith a cylindercasing having a movable sleeve and a piston in said sleeve, said sleevebeing moved by frlctlon with the piston, of

an electro-magnet for controlling the movement of said sleeve, and aswitch device for controlling the circuit of said electromagnet. V

'7.'In a fluid compressor, the combination with a cylinder casing havinga movable sleeve and a piston in said sleeve, said sleeve being moved byfriction with the piston, of an electro-magnet for controlling themovement of said sleeve, and a switch'device in the circuit of saidelectro-magnet and Opera tive to close said circuit to effect theenergization of said electro-magnet when the pressure of fluidcompressed by the compressor has been increased to a predetermineddegree.

8., In a fluid compressor, the combination with a cylinder casing havinga movable sleeve valve and a piston in said sleeve, of an electro-magnetsurrounding said sleeve, a collar on said sleeve serving as an armatureto said magnet, and a switch device for controlling the circuit of saidelectro-magnet.

In testimony whereof I have hereunto set my hand.

SIDNEY e. DOWN.

